How severe is CVE-2020-3866?

CVE-2020-3866 has a CVSS 3.x base score of 5.5, rated medium severity. It is exploitable over local access with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity high, and availability none.

Is CVE-2020-3866 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (48th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-3866?

CVE-2020-3866 affects Apple Mac Os X. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2020-3866?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2020-3866 published?

CVE-2020-3866 was published on 2020-02-27 and last updated on 2026-06-17.

CVE-2020-3866

CVE-2020-3866 is a medium-severity vulnerability in Apple Mac Os X with a CVSS 3.x base score of 5.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.

Key facts

Severity: Medium (CVSS 3.x base score 5.5)
CVSS v2: 4.3
EPSS exploit prediction: 1% (48th percentile)
Actively exploited: Not listed in CISA KEV
Affected product: Apple Mac Os X
Published: 2020-02-27
Last modified: 2026-06-17

Description

This was addressed with additional checks by Gatekeeper on files mounted through a network share. This issue is fixed in macOS Catalina 10.15.3. Searching for and opening a file from an attacker controlled NFS mount may bypass Gatekeeper.

Frequently asked questions

What is CVE-2020-3866?: This was addressed with additional checks by Gatekeeper on files mounted through a network share. This issue is fixed in macOS Catalina 10.15.3. Searching for and opening a file from an attacker controlled NFS mount may bypass Gatekeeper.
How severe is CVE-2020-3866?: CVE-2020-3866 has a CVSS 3.x base score of 5.5, rated medium severity. It is exploitable over local access with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity high, and availability none.
Is CVE-2020-3866 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (48th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-3866?: CVE-2020-3866 affects Apple Mac Os X. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2020-3866?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2020-3866 published?: CVE-2020-3866 was published on 2020-02-27 and last updated on 2026-06-17.

References

https://support.apple.com/HT210919

Affected products (1)

cpe:2.3:o:apple:mac_os_x:*:*:*:*:*:*:*:*

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